Machines of the above type are known, in which the blanks are fed along a given path on a conveying surface, and interact with operating devices, such as folding, gluing or pressing devices, arranged successively along the path.
The conveying surface may comprise one or more belts, or a number of side by side powered rollers with respective axes crosswise to the path. Whichever the case, the blanks, as they are fed forward, must be maintained contacting the conveyor belts or rollers at all times, which is normally done using pressure devices comprising a number of idle rollers or wheels.
EP-A-1 424 191 describes a machine comprising a powered-roller conveying surface; and a number of operating devices and idle-roller pressure devices, which are supported over the machine frame by gantry-type supporting members to permit flexible placement along the path.
Using a combination of powered rollers and accurately but flexibly supported pressure devices provides for conveying the blanks accurately with no lateral slip.
In known machines of the above type, however, a certain amount of slippage still remains between the blanks and the conveyor rollers, and which known pressure devices fail to eliminate.